Conventional methods of the kind named at the beginning are available. For example, there are methods that use one signal flow respectively for different operating modes. For example, German Patent Application No. DE 101 60 819 B4 describes a control of the overrun operation of vehicle drives in which a driver is able to choose between different operating modes. The signal flow represents a control variable that defines one torque respectively for the drive units as a function of a drive setpoint torque. In the process, parameters, such as the charging state of an electric accumulator, for example, are taken into account in different manners in the different signal flows. In the event of a switch from one operating mode to the other, for example, in the event of a switch from the hybrid mode to the electric mode, the internal combustion engine may “rev up” due to the sudden loss of a counter torque when a coupling between the internal combustion engine and the electric machine is opened and may thereby cause unnecessary losses in the internal combustion engine on the one hand, and on the other hand may be experienced as uncomfortable by a driver. To create a continuous, “smooth” transition between the operating modes, costly functionalities are used that filter or ramp fluctuations caused by switching the operating mode.